As communication technologies further advance, serial interfaces have been widely employed in communication protocols such as Ethernet and PCI Express. For example, serial interfaces have been widely used to convert signals between parallel bus-connected devices and high-speed serial communication systems. In order to enable the movement of a large amount of data between parallel and serial systems, a serializer/deserializer is employed to convert data from a parallel data form to a serial data form in the high-speed serial communication systems.
The serial communication system in its simplest form may comprise a transmitter, a communication channel and a receiver. The transmitter may receive a parallel set of bits and convert them into serial signals through suitable digital circuits such as multiplexers and shift registers. The serial signals are transmitted over the communication channel to the receiver.
The receiver may comprise a clock and data recovery circuit, which is capable of extracting a clock signal from the received serial signals. The recovered clock is used to accurately sample the received data.
The receiver may further comprise a pre-amplifier, a comparator coupled to the output of the pre-amplifier, and a decoder. The pre-amplifier is employed to improve the gain of the received signals and reduce input referred noise. The comparator may contain a suitable amplifier such as a static amplifier or a clocked regenerative amplifier. The decoder is coupled to the output of the comparator. The decoder may be used to achieve advanced modulation.
The clocked regenerative amplifier is also known as a latch comparator. The latch comparator may receive a clock signal and two differential input signals. The latch comparator samples the differential input signals at clock edges (e.g., the clock edge from a logic low state to a logic high state) and generates a binary 0 or 1 at the output of the latch comparator. The latch comparator is widely used in various applications such as memories, analog-to-digital converters (ADC) and high speed serial links.